Method and apparatus for providing service in wireless communication system

ABSTRACT

The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. A method for replacement of a DNN and/or S-NSSAI in a wireless communication system is provided.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based on and claims priority under 35 U.S.C. §119(a) of a Korean patent application number 10-2019-0071053, filed onJun. 14, 2019, in the Korean Intellectual Property Office, thedisclosure of which is incorporated by reference herein in its entirety.

BACKGROUND 1. Field

The disclosure relates to a method and apparatus for providing a servicerequested by a terminal in a mobile communication system.

2. Description of Related Art

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a ‘Beyond 4G Network’ or a‘Post LTE System’. The 5G communication system is considered to beimplemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, soas to accomplish higher data rates. To decrease propagation loss of theradio waves and increase the transmission distance, the beamforming,massive multiple-input multiple-output (MIMO), Full Dimensional MIMO(FD-MIMO), array antenna, an analog beam forming, large scale antennatechniques are discussed in 5G communication systems. In addition, in 5Gcommunication systems, development for system network improvement isunder way based on advanced small cells, cloud Radio Access Networks(RANs), ultra-dense networks, device-to-device (D2D) communication,wireless backhaul, moving network, cooperative communication,Coordinated Multi-Points (CoMP), reception-end interference cancellationand the like. In the 5G system, Hybrid FSK and QAM Modulation (FQAM) andsliding window superposition coding (SWSC) as an advanced codingmodulation (ACM), and filter bank multi carrier (FBMC), non-orthogonalmultiple access (NOMA), and sparse code multiple access (SCMA) as anadvanced access technology have been developed.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the Internetof Things (IoT) where distributed entities, such as things, exchange andprocess information without human intervention. The Internet ofEverything (IoE), which is a combination of the IoT technology and theBig Data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology”,“wired/wireless communication and network infrastructure”, “serviceinterface technology”, and “Security technology” have been demanded forIoT implementation, a sensor network, a Machine-to-Machine (M2M)communication, Machine Type Communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected things. IoT maybe applied to a variety of fields including smart home, smart building,smart city, smart car or connected cars, smart grid, health care, smartappliances and advanced medical services through convergence andcombination between existing Information Technology (IT) and variousindustrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies, suchas a sensor network, Machine Type Communication (MTC), andMachine-to-Machine (M2M) communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud RadioAccess Network (RAN) as the above-described Big Data processingtechnology may also be considered to be as an example of convergencebetween the 5G technology and the IoT technology.

The above information is presented as background information only toassist with an understanding of the disclosure. No determination hasbeen made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

SUMMARY

Aspects of the disclosure are to address at least the above-mentionedproblems and/or disadvantages and to provide at least the advantagesdescribed below. Accordingly, an aspect of the disclosure is to providea solution for processing a case where parameters (for example, a datanetwork name (DNN), single network slice selection assistanceinformation (S-NSSAI), and the like), transmitted to a network function(NF) by a user equipment (UE), are not valid, or a case where theparameters cannot be provided by a mobile communication system (forexample, a 5th generation system (5GS), an evolved packet system (EPS),and the like).

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

According to an embodiment of the disclosure, the case where theparameters transmitted to the NF by the UE are not valid may include thecase where UE configuration information (for example, UE route selectionpolicy (URSP), local configuration, and the like) stored by the UE isnot the latest information, the case where there is no UE configurationinformation, or the like.

According to an embodiment of the disclosure, the case where parameters,transmitted to the NF by the UE, cannot be provided by a mobilecommunication system may include the case where the parameters cannot beprovided due to an operator policy, the case where the parameters cannotbe provided at the current location of the UE, the case where theparameters cannot be provided due to a temporary failure in the mobilecommunication system, or the case where the parameters cannot beprovided due to a roaming contract.

In accordance with an aspect of the disclosure, a method performed by anaccess and mobility management function (AMF) in a mobile communicationsystem is provided. The method includes selecting a policy controlfunction (PCF) for a replacement of DNN, based on a receivedregistration request message from a user equipment (UE), transmitting,to the PCF, allowed network slice selection assistance information(NSSAI) for the UE, receiving, from the PCF, first list information onthe replacement of DNN, based on the allowed NSSAI, receiving, from theUE, a protocol data unit (PDU) session establishment request messageincluding single NSSAI (S-NSSAI) for a PDU session and a UE requestedDNN, and determining to perform a replacement of the UE requested DNN,based on the first list information.

In accordance with another aspect of the disclosure, a method performedby a policy control function (PCF) in mobile a communication system isprovided. The method includes transmitting, to a network repositoryfunction (NRF), a network function (NF) register request messageincluding capability information of the PCF to indicate whether or notthe PCF supports a replacement of DNN, receiving, from the NRF, an NFregister request response message for an acknowledgement that an NFregister request is accepted, receiving, from an access and mobilitymanagement function (AMF), allowed network slice selection assistanceinformation (NSSAI) for a user equipment (UE), and transmitting, to theAMF, first list information on the replacement of DNN, based on theallowed NSSAI, wherein a protocol data unit (PDU) session establishmentrequest message including single NSSAI (S-NSSAI) for the PDU session anda UE requested DNN is transmitted to the AMF from the UE and areplacement of the UE requested DNN is performed based on the first listinformation.

In accordance with another aspect of the disclosure, a method performedby a network repository function (NRF) in a mobile communication systemis provided. The method includes receiving, from a policy controlfunction (PCF), a network function (NF) register request messageincluding capability information of the PCF to indicate whether or notthe PCF supports a replacement of DNN, transmitting, to the PCF, an NFregister request response message for an acknowledgement that an NFregister request is accepted, receiving, from an access and mobilitymanagement function (AMF), an NF discovery request message includingcapability information to indicate that the PCF supporting a capabilityfor the replacement of DNN is preferred, and transmitting, to the AMF,an NF discovery response message including capability information toindicate whether or not the PCF supports the replacement of DNN.

In accordance with another aspect of the disclosure, an access andmobility management function (AMF) in a mobile communication system isprovided. The AMF includes a transceiver, and at least one processorconfigured to select a policy control function (PCF) for a replacementof DNN, based on a received registration request message from a userequipment (UE), control the transceiver to transmit, to the PCF, allowednetwork slice selection assistance information (NSSAI) for the UE,control the transceiver to receive, from the PCF, first list informationon the replacement of DNN, based on the allowed NSSAI, control thetransceiver to receive, from the UE, a protocol data unit (PDU) sessionestablishment request message including single NSSAI (S-NSSAI) for a PDUsession and a UE requested DNN, and determine to perform a replacementof the UE requested DNN, based on the first list information.

In accordance with another aspect of the disclosure, a policy controlfunction (PCF) in mobile a communication system is provided. The PCFincludes a transceiver, and at least one processor configured to controlthe transceiver to transmit, to a network repository function (NRF), anetwork function (NF) register request message including capabilityinformation of the PCF to indicate whether or not the PCF supports areplacement of DNN, control the transceiver to receive, from the NRF, anNF register request response message for an acknowledgement that an NFregister request is accepted, control the transceiver to receive, froman access and mobility management function (AMF), allowed network sliceselection assistance information (NSSAI) for a user equipment (UE), andcontrol the transceiver to transmit, to the AMF, first list informationon the replacement of DNN, based on the allowed NSSAI, wherein aprotocol data unit (PDU) session establishment request message includingsingle NSSAI (S-NSSAI) for the PDU session and a UE requested DNN istransmitted to the AMF from the UE and a replacement of the UE requestedDNN is performed based on the first list information.

In accordance with another aspect of the disclosure, a networkrepository function (NRF) in a mobile communication system is provided.The NRF comprising a transceiver, and at least one processor configuredto control the transceiver to receive, from a policy control function(PCF), a network function (NF) register request message includingcapability information of the PCF to indicate whether or not the PCFsupports a replacement of DNN, control the transceiver to transmit, tothe PCF, an NF register request response message for an acknowledgementthat an NF register request is accepted, control the transceiver toreceive, from an access and mobility management function (AMF), an NFdiscovery request message including capability information to indicatethat the PCF supporting a capability for the replacement of DNN ispreferred, and control the transceiver to transmit, to the AMF, an NFdiscovery response message including capability information to indicatewhether or not the PCF supports the replacement of DNN.

According to an embodiment of the disclosure, in a case where parameters(for example, DNN, S-NSSAI, and the like) transmitted by a UE to an NFare not valid or in a case where a mobile communication system (forexample, 5GS, EPS, and the like) cannot provide the parameters, it ispossible to prevent a service failure or a decrease in customer servicequality by replacing the parameters transmitted by the UE with availableparameters, instead of rejecting (session releasing) a request from theUE.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1A illustrates a system structure of a 5th generation system (5GS)according to an embodiment of the disclosure;

FIG. 1B illustrates an interworking structure of a 5GS and an evolvedpacket system (EPS) according to an embodiment of the disclosure;

FIG. 2 illustrates a user equipment (UE) registration procedureaccording to an embodiment of the disclosure;

FIG. 3 illustrates a network function (NF) registration, discovery, andselection procedure according to an embodiment of the disclosure;

FIG. 4 illustrates a Protocol Data Unit (PDU) session establishmentprocedure according to an embodiment of the disclosure;

FIG. 5 illustrates a procedure for updating UE configuration informationaccording to an embodiment of the disclosure;

FIG. 6 illustrates a structure of a UE according to an embodiment of thedisclosure;

FIG. 7 illustrates a structure of a base station according to anembodiment of the disclosure;

FIG. 8 illustrates a structure of an access and mobility managementfunction (AMF) according to an embodiment of the disclosure;

FIG. 9 illustrates a structure of a PCF according to an embodiment ofthe disclosure; and

FIG. 10 illustrates a structure of a Network Repository Function (NRF)or a service communication proxy (SCP) according to an embodiment of thedisclosure.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thedisclosure. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of thedisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of thedisclosure is provided for illustration purpose only and not for thepurpose of limiting the disclosure as defined by the appended claims andtheir equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

The advantages and features of the disclosure and methods for achievingthe same will be apparent by making reference to embodiments asdescribed below in conjunction with the accompanying drawings. However,the disclosure is not limited to the embodiments set forth below, butmay be implemented in various different forms. The following embodimentsare provided only to completely disclose the disclosure and inform thoseskilled in the art of the scope of the disclosure, and the disclosure isdefined only by the scope of the appended claims. Throughout thespecification, the same reference numerals designate the same elements.

Terms used to identify an access node used in the following description,terms referring to a network entity or network functions (NFs), termsreferring to messages, terms referring to an interface between networkentities, terms referring to various identification information, or thelike are exemplified for convenience of explanation. Accordingly, thedisclosure is not limited to the terms described below, and other termsindicating objects having equivalent technical meanings may be used.

For convenience of explanation below, the disclosure uses terms andnames defined in 3rd generation partnership project long term evolution(3GPP LTE) and 5G standards. However, the disclosure is not limited bythe terms and names, and can be applied to systems conforming to otherstandards.

Meanwhile, in the disclosure, the term “service” may be interchangeablyused in order to refer to performing a request from anothercommunication device (or NF) by a specific communication device (or NF)(i.e., referring to an NF Service), to refer to a service provided by amobile communication operator (i.e., referring to a voice service, atext service, a data service, and the like), and to refer to a serviceprovided by an over the top (OTT) operator (i.e., referring to amessenger service, a game service, and the like).

A mobile communication system provides UE access (attach)/registrationand session connection (PDN connection, PDU session) in order to providea service. To this end, a protocol between the UE and the NF of themobile communication system has been defined, and the UE and the NFexchange various parameters defined by a control plane signalingprotocol.

FIG. 1A illustrates a system structure of a 5GS according to anembodiment of the disclosure.

Referring to FIG. 1A, a 5G core network includes an access and mobilitymanagement function (AMF) 120, a session management function (SMF) 135,a user plane function (UPF) 130, a policy control function (PCF) 140, aunified data management (UDM) 145, a network slice selection function(NSSF) 160, an authentication server function (AUSF) 165, an applicationfunction (AF) 170, a data network (DN) 175, or the like. A UE 100 mayaccess a 5G core network through a base station (RAN) 110. One or moreNFs may interact with a network repository function (NRF) via Nnrfinterfaces.

FIG. 1B illustrates an interworking structure of a 5GS and an EPSaccording to an embodiment of the disclosure.

Referring to FIG. 1B, the 5GS may include a new radio (NR) base station(NG RAN) 110, an AMF 120, a SMF 135, a UPF 130, a PCF 140, and a UDM145. The EPS may include an evolved universal terrestrial radio access(E-UTRA) base station 105, a mobility management entity (MME) 115, aserving gateway (SGW) 125, a PDN gateway (PGW)-U 130, a PGW-C 135, apolicy and charging rules function (PCRF) 140, and a home subscriberserver (HSS) 145. The UDM 145 of the 5GS and the HSS 145 of the EPS maybe configured as one combo node (hereinafter, referred to as “UDM+HSS”).The SMF 135 of the 5GS and the PGW-C 135 of the EPS may be configured asone combo node (hereinafter, referred to as “SMF+PGW-C”). The UPF 130 ofthe 5GS and the PGW-U 130 of the EPS may be configured as one combo node(hereinafter, referred to as “UPF+PGW-U”). The UE 100 may access the MME135 of the EPS through the E-UTRA base station 105 so as to use an EPSnetwork service. Further, the UE 100 may access the AMF 120 of the 5GSthrough the NR base station 110 so as to use a 5GS network service.

The AMF 120 and MME 115 are network functions (NFs) that manage wirelessnetwork access and mobility for the UE. The SMF 135, PGWs 130 and 135,and the SMF+PGW-C 135 are NFs that manage a session for the UE, thesession information may include quality of service (QoS) information,charging information, and information relating to packet processing. TheUPF 130, the PGWs 130 and 135, and the UPF+PGW-U 130 are NFs thatprocess user traffic (user plane traffic) and are subject to control bythe SMF 135, the PGWs 130 and 135, the SMF+PGW-C 135. The PCF 140, thePCRF 140, and the PCF+PCRF 140 are NFs that manage operator policies forproviding services in a wireless communication system. The UDM 145, theHSS 145, and the UDM+HSS 145 nodes are NFs that store and manage UEsubscription information. A unified data repository (UDR) 150 is an NFthat stores and manages data. The UDR may store UE subscriptioninformation and provide the UE subscription information to the UDM. Inaddition, the UDR may store operator policy information and provide theoperator policy information to the PCF.

Embodiment 1

Embodiment 1 describes a method for configuring an NF, by whichparameters transmitted by a UE can be replaced with availableparameters.

FIG. 2 illustrates a UE registration procedure according to anembodiment of the disclosure.

Referring to FIG. 2, in operation 203, a UE 100 may transmit aregistration request message. The UE 100 may include, in theregistration request message, capability information (e.g., DNNreplacement, S-NSSAI replacement, DNN/S-NSSAI (both) replacement, andthe like) of the UE 100. Further, the UE 100 may include, in theregistration request message, slice information (e.g., Requested NSSAI,and the like) to be used by accessing a network by the UE 100. Inoperation 206, the base station 110, which has received the registrationrequest message from the UE 100, may select an AMF to which the receivedmessage is to be transmitted, based on information (e.g., RequestedNSSAI, UE 5G-globally unique temporary identifier (GUTI) or the like)received from the UE 100 in operation 203. In operation 209, the basestation 110 may transmit the registration request message to the AMF(new AMF) 120 selected in operation 206. In the case of being capable ofdiscovering an old AMF 200 based on the received UE 5G-GUTI information,the AMF 120 may perform operations 212, 215, and 218, and may acquirethe context of the UE 100 from the old AMF 200. In operation 221, theAMF 120 may select the UDM 145. In operation 224 a, the AMF 120 mayperform registration, as an AMF serving the UE 100, in the UDM 145. Inoperation 224 b, the AMF 120 may acquire, from the UDM 145, informationrelated to the UE 100 (e.g., access and mobility subscription data, SMFselection subscription data, UE context, subscribed DNNs, subscribedS-NSSAIs, and the like). In operation 224 c, the AMF 120 may register(subscribe) for an event related to the UE 100, provided by the UDM 145.Upon detecting that the AMF serving the UE 100 is changed from the oldAMF 200 to the AMF 120, the UDM 145 may transmit a deregistrationnotification message to the old AMF 200 in operation 224 d. In operation224 e, the old AMF 200 may cancel the event registration previouslyregistered in the UDM 145. In operation 227, the AMF 120 may perform aPCF selection procedure. The PCF selection procedure will be describedin operations 227 a, 227 b, and 227 c of FIG. 3. In operation 230, theAMF 120 may establish an AM policy association with the PCF 140 selectedin operation 227. The process of establishing the AM policy associationbetween AMF 120 and the PCF 140 will be described in operations 230 a,230 b, and 230 c of FIG. 3. In operation 209, the AMF 120 may determinea network capability (e.g., DNN replacement, S-NSSAI replacement,DNN/S-NSSAI (both) replacement, and the like) to be provided to the UE100, based on the information received from the UE 100 and/or the AMpolicy association established with the PCF 140 in operation 230. Inoperation 233, the AMF 120 may update or release a PDU sessionassociated with the UE 100. In operation 236 a, the AMF 120 may transmita registration accept message to the UE 100. The AMF 120 may includeslice information (e.g., Allowed NSSAI, and the like), which isavailable by accessing a network by the UE 100, in the registrationaccept message. In addition, the AMF 120 may include, in theregistration accept message, network capability information (e.g., DNNreplacement, S-NSSAI replacement, DNN/S-NSSAI (both) replacement)determined by the AMF 120. In operation 236 b, the AMF 120 may establishUE policy association with the PCF 140 selected in operation 227. Theprocess of establishing the UE policy association between the AMF 120and the PCF 140 is described in operations 230 a, 230 b, and 230 c ofFIG. 3. In operation 239, the UE 100 may transmit a registrationcomplete message to the AMF 120. In operation 242, the AMF 120 mayperform a Nudm_SDM_Info procedure with the UDM 145. In operation 245,the AMF 120 may perform the Nudm_UECM_Update procedure with the UDM 145.

FIG. 3 illustrates an NF registration, discovery, and selectionprocedure according to an embodiment of the disclosure.

Referring to FIG. 3, in operation 303, the PCF 140 (or PCF 140/400) maytransmit an Nnrf_NFManagement_NFRegister Request message in order toregister an NF profile of the PCF 140 itself in a network repositoryfunction (NRF) 300. The Nnrf_NFManagement_NFRegister Request message mayinclude an NF ID of the PCF 140, in which the NF ID refers to the PCF140, and functions supportable by the PCF 140, that is, NF services(e.g., DNN replacement, S-NSSAI replacement, DNN/S-NSSAI (both)replacement, one or more DNNs supportable by the PCF 140, one or moreS-NSSAIs supportable by the PCF 140, and the like). In operation 306,the NRF 300 may process the request from the PCF 120, received inoperation 303, as follows. The NRF 300 may store the NF ID of the PCF140 and the NF services supportable by the PCF 140. In operation 309,the NRF 300 may transmit an Nnrf_NFManagement_NFRegister responsemessage to the PCF 140 and thus may provide notification that NF ServiceRegistration has been completed.

After completing the NF registration in the NRF 300 through operations303 to 309, the PCF 140 may perform operations 312 to 318 in order toupdate the NF service in the case where a change in the NF servicesupportable by the PCF 140 occurs. In operation 312, the PCF 140 maytransmit an Nnrf_NFManagement_NFUpdate Request message to the NRF 300.The Nnrf_NFManagement_NFUpdate Request message may include the NF ID ofthe PCF 140, in which the NF ID refers to the PCF 140, and the NFservice supportable by the PCF 140. In operation 315, the NRF 300 maydiscover NF profile information corresponding to the NF ID of the PCF140, received in operation 312. The NRF 300 may update NF profileinformation of the PCF 140, stored in the NRF 300, with the NF servicereceived in operation 312. In operation 318, the NRF 300 may transmit anNnrf_NFManagement_NFUpdate response message to the PCF 140 and thusprovide notification that the NF service update has been completed. Forexample, the PCF 140 may indicate that DNN replacement is possible, asthe NF service of the PCF 140 in operation 303. Thereafter, the PCF 140may indicate that DNN replacement is not possible, as the NF service ofthe PCF 140 in operation 312.

The NF (e.g., AMF, SMF, PCF, UPF, and the like) configuring a 5G systemmay register and update an NF profile provided by each NF in the NRF300, as described in operations 303 to 309 and operations 312 to 318.

In addition, the NF registration, discovery, and update functionsprovided by the NRF shown in FIG. 3 may be similarly provided by aservice communication proxy (SCP) 300.

As shown in FIG. 2, the AMF 120 according to an embodiment may select aPCF during the registration procedure of the UE 100 and establish apolicy association with the selected PCF.

In operation 227, the AMF 120 may use an NF discovery service, which isprovided by the NRF 300 for PCF selection.

In operation 227 a, the AMF 120 may transmit an Nnrf_NFDiscovery requestto the NRF 300. The Nnrf_NFDiscovery request, transmitted by the AMF120, may include at least one of an NF type (for example, PCF) to bediscovered by the AMF 120, and an NF support function (for example, DNNreplacement, S-NSSAI replacement, DNN/S-NSSAI (both) replacement, andthe like) to be discovered by the AMF 120, the current location of theUE 100 (e.g., cell ID, tracking area identity (TAI), and the like), theidentifier of the UE 100 (e.g., a subscription permanent identifier(SUPI), 5G-GUTI, and the like), and the NF ID of the AMF 120. Inoperation 227 b, the NRF 300 may process an NF discovery request,received in operation 227 a, based on the NF profile informationregistered in the NRF 300. For example, in operation 227 a, in the casewhere the AMF 120 requests discovering a PCF capable of performing DNNreplacement for the UE 100, the NRF 300 may select one or more PCFscapable of performing DNN replacement among PCFs registered in the NRF300. In addition, the NRF 300 may select one or more PCFs, close to thecurrent location of the UE 100 and/or the location of the AMF 120, amongone or more PCFs capable of performing DNN replacement. TheNnrf_NFDiscovery response message, which is transmitted by the NRF 300to the AMF 120 in operation 227 c, may include one or more pieces of PCFinformation selected by the NRF 300 (for example, the NF ID of the PCF,and NF services supported by the PCF (for example, DNN replacement,S-NSSAI replacement, DNN/S-NSSAI (both) replacement, one or more DNNssupportable by PCF 120, one or more S-NSSAIs supportable by PCF 120, andthe like), and the like) The AMF 120 may select one PCF based on PCFinformation received from the NRF 300. For example, in the case whereone piece of PCF information is received from the NRF 300, the AMF 120may select a PCF, which is selected by the NRF 300 and notified to theAMF 120. Alternatively, in the case where multiple pieces of PCFinformation are received from the NRF 300, the AMF 120 may select a PCFbased on the local configuration of the AMF 120, the location of the UE100, and the location of the PCF and the like. Alternatively, the AMF120 may select a PCF based on the local configuration stored in the AMF120 without using an NF discovery function provided by the NRF 300, thatis, without performing operation 227 a to operation 227 c.

In operation 230, the AMF 120 may establish an AM policy associationwith the selected PCF 140. In addition, in operation 236 b, the AMF 120may establish a UE policy association with the selected PCF 140.

In operations 230 a to 236 ba, Npcf_AMPolicyControl_Create toNpcf_UEPolicyControl_Create message, transmitted by the AMF 120 to thePCF 140, may include at least one of: the capability of the AMF 120 (forexample, DNN replacement, S-NSSAI replacement, DNN/S-NSSAI (both)replacement, and the like), an indication requesting DNN replacementand/or S-NSSAI replacement; subscribed DNNs and/or subscribed S-NSSAIsof the UE 100, received by the AMF 120 from UDM 145 in operation 224 b;the identifier of the UE 100 (e.g., SUPI, 5G-GUTI, and the like), a homepublic land mobile network (HPLMN) ID of the UE 100; and a location ofthe UE 100. In operations 230 b to 236 bb, the PCF 140 may determinepolicy information to be provided to the AMF 120, based on theinformation received from the AMF 120 in operations 230 a to 236 ba. Forexample, in the case where the AMF 120 requests DNN replacement, the PCF140 may determine a DNN list configured by one or more DNNs for DNNreplacement. The DNN list may include one or more pieces of S-NSSAIinformation that can be used together with respective DNNs configuringthe DNN list. Alternatively, in the case where the AMF 120 requestsS-NSSAI replacement, the PCF 140 may determine an S-NSSAI list (or maybe referred to as an NSSAI list) configured by one or more S-NSSAIs forS-NSSAI replacement. The S-NSSAI list may include one or more pieces ofDNN information that can be used together with respective S-NSSAIsconfiguring the S-NSSAI list. The DNN list and/or the S-NSSAI list maybe configured differently according to the subscribed DNNs of the UE100, the HPLMN of the UE 100, the location of the UE 100, and the like.In order to determine the HPLMN of the UE 100, the PCF 140 may use theHPLMN ID of the UE 100, received from the AMF 120, or the HPLMN ID ofthe UE 100, included in the identifier of the UE 100 (e.g., SUPI). TheDNN list and/or S-NSSAI list may be configured by a blacklist and/or awhitelist. The Npcf_AMPolicyControl_Create response toNpcf_UEPolicyControl_Create response message, transmitted by the PCF 140to the AMF 120 in operations 230 c to 236 bc, may include a DNN listand/or an S-NSSAI list, determined by the PCF 140. The AMF 120 may storethe DNN list and/or the S-NSSAI list, received from the PCF 140, and mayuse the DNN list and/or the S-NSSAI list in subsequent operations andprocedures of the AMF 120.

Embodiment 2

Embodiment 2 describes a method for replacing a parameter transmitted bya UE with an available parameter.

FIG. 4 illustrates a PDU session establishment procedure according to anembodiment of the disclosure.

Referring to FIG. 4, in operation 403, the UE 100 may transmit a PDUsession establishment request message. The PDU session establishmentrequest message may include a DNN and/or S-NSSAI, determined by the UE100 based on local configuration information of the UE 100, and a PDUsession ID assigned by the UE 100. The AMF 120 may determine whether toperform DNN replacement or S-NSSAI replacement based on at least one oflocal configuration, information (e.g., DNN list and/or S-NSSAI list)received from the PCF 140 in operations 230 c to 236 bc of FIG. 3, andUE requested DNN or a UE requested S-NSSAI information, received from UE100 in operation 403.

For example, in the case where the DNN list and/or the S-NSSAI list,received from the PCF 140 through the procedure described in FIGS. 2 and3, is a blacklist, and if the DNN or S-NSSAI included in the list isreceived from the UE 100 in operation 403, the AMF 120 may be aware thatthe DNN or S-NSSAI, received from the UE 100, are to be subject to DNNreplacement or S-NSSAI replacement. Alternatively, if a DNN or S-NSSAI,which is not included in the list from the UE 100 in operation 403, isreceived from the UE 100 in operation 403, the AMF 120 may be aware thatthe DNN or S-NSSAI, received from the UE 100, are not to be subject toDNN replacement or S-NSSAI replacement.

According to another example, in the case where the DNN list and/or theS-NSSAI list received from the PCF 140 through the procedures describedin FIGS. 2 and 3 is a whitelist, and if the DNN or S-NSSAI included inthe list is received from the UE 100 in operation 403, the AMF 120 maybe aware that the DNN or S-NSSAI, received from the UE 100, are not tobe subject to DNN replacement or S-NSSAI replacement. Alternatively, ifa DNN or S-NSSAI, which is not included in the list, is received fromthe UE 100 in operation 403, the AMF 120 may be aware that the DNN orS-NSSAI, received from the UE 100, are to be subject to DNN replacementor S-NSSAI replacement.

According to another example, if the AMF 120 determines that the DNN orS-NSSAI, received from the UE 100, are not to be subject to DNNreplacement or S-NSSAI replacement and that the corresponding DNN orS-NSSAI cannot be supported, the AMF 120 may determine to reject the PDUsession establishment request, requested by the UE, and may transmit anappropriate reject cause (e.g., DNN not supported, S-NSSAI notsupported, and the like) to the UE 100 through operations 445 and 448.

The AMF 120 that has determined to perform DNN replacement and/orS-NSSAI replacement may perform operation 404. A message in operation404 may include at least one of the requested DNN, the requestedS-NSSAI, and the identifier of the UE 100 (for example, SUPI, 5G-GUTI,and the like), which are subject to replacement. In operation 405, thePCF 140 may make a policy determination.

For example, in the case where the AMF 120 requests DNN replacement forthe requested DNN, the PCF 140 may determine a selected DNN to replacethe received requested DNN (hereinafter, selected DNN or replaced DNN).In operation 406, the PCF 140 may transmit a reply message to the AMF120. The reply message transmitted by the PCF 140 to the AMF 120 mayinclude at least one of the selected DNN selected by the PCF 140, therequested DNN requested in operation 404, and S-NSSAI that can be usedtogether with the selected DNN.

According to still another example, in the case where the AMF 120requests S-NSSAI replacement for the requested S-NSSAI, the PCF 140 maydetermine the selected S-NSSAI to replace the received requestedS-NSSAI. In operation 406, the PCF 140 may transmit a reply message tothe AMF 120. The reply message transmitted by the PCF 140 to the AMF 120may include at least one of the selected S-NSSAI selected by the PCF140, the requested S-NSSAI requested in operation 404, and the DNNs thatcan be used together with the selected S-NSSAI.

In operation 406, the AMF 120 may store the information received fromthe PCF 140 as a UE context. For example, the AMF 120 may store at leastone of: the PDU session ID, the requested DNN, and the requestedS-NSSAI, which are received from the UE 100, and the selected DNN andthe selected S-NSSAI, received from the PCF 140, as the UE context. Inthe case where the selected DNN and/or the selected S-NSSAI is receivedfrom the PCF 140, the AMF 120 may use the selected DNN and/or theselected S-NSSAI instead of the requested DNN and/or the requestedS-NSSAI in subsequent operations.

If the AMF 120 according to an embodiment acquires the DNN list and/orthe S-NSSAI list from the PCF 140 during the process of AM policyassociation, that is, in operation 230 c, the message in operation 404may be an Npcf_AMPolicyControl_Update request message, and the messagein operation 406 may be an Npcf_AMPolicyControl_Update response message.Alternatively, in the case where the AMF 120 acquires the DNN listand/or the S-NSSAI list from the PCF 140 during the process of UE policyassociation, that is, in operation 236 bc, the message in operation 404may be an Npcf_UEPolicyControl_Update request message and the message inoperation 406 may be an Npcf_UEPolicyControl_Update response message.

In operation 407, the AMF 120 may perform SMF selection forestablishment of a PDU session. The SMF selection may be performedthrough the NRF, similarly to operations 227 a, 227 b, and 227 c of FIG.3. For example, the AMF 120 may transmit, to the NRF 300, anNnrf_NFDiscovery request message for discovering an SMF supporting DNNand/or S-NSSAI for a PDU session. If the selected DNN and/or theselected S-NSSAI is received from the PCF 140, the DNN and/or theS-NSSAI, requested by the AMF 120 to the NRF 300, may be the selectedDNN and/or selected S-NSSAI, received from the PCF 140. Alternatively,if the selected DNN and/or selected S-NSSAI is not received from the PCF140, the DNN and/or S-NSSAI requested by the AMF 120 to the NRF 300 maybe the requested DNN and/or the requested S-NSSAI, received from the UE100.

In operation 409, the AMF 120 may transmit anNsmf_PDUSession_CreateSMContext Request message to a selected SMF 135.The Nsmf_PDUSession_CreateSMContext Request may include at least one ofthe PDU session ID, the requested DNN, the requested S-NSSAI, theselected DNN, and the selected S-NSSAI.

In operation 412, the SMF 135 may perform a subscriptionretrieval/subscription for update procedure with the UDM 145.

In operation 415, the SMF 135 may transmit anNsmf_PDUSession_CreateSMContext response message to the AMF 120.

In operation 418, the UE 100 may perform a PDU sessionauthentication/authorization procedure.

In operation 421, the AMF 120 may perform a PCF selection procedure fora PDU session. The PCF selection procedure may follow the procedureshown in FIG. 3. The PCF (hereinafter, referred to as SM PCF 400)selected for the PDU session may be the same as or different from theselected PCF (hereinafter, referred to as AM PCF 140) during theregistration procedures illustrated in FIG. 2.

In operation 424, the AMF 120 may perform an SM policy associationestablishment procedure with the PCF 400.

In operation 427, the AMF 120 may perform a UPF selection procedure forthe PDU session.

In operation 430, the AMF 120 may perform an SMF initiated SM policyassociation modification procedure with the PCF 400.

In operation 433, the SMF 135 may transmit an N4 session establishmentrequest message to the UPF 130. In operation 436, the UPF 130 maytransmit an N4 session establishment response message to the SMF 135.

In operation 439, the SMF 135 may transmit an N2 PDU session requestmessage to the AMF 120. The N2 PDU session request message may include aPDU session establishment accept message, which is a NAS message to betransmitted by the AMF 120 to the UE 100. In operation 442, the AMF 120may transmit an N2 PDU session response message to the SMF 135.

In operations 445 and 448, the AMF 120 may transmit a PDU sessionestablishment accept message to the UE 100 through the base station 110.The PDU session establishment accept message may include at least one ofthe PDU session ID, the requested DNN, the requested S-NSSAI, theselected DNN, and the selected S-NSSAI. For example, if DNN replacementis not performed, the AMF 120 may include only the requested DNN in thePDU session establishment accept message. Alternatively, if DNNreplacement has been performed and DNN replacement is to be performedwithout recognition of the UE 100, the AMF 120 may include only therequested DNN in the PDU session establishment accept message withoutthe selected DNN. Alternatively, if DNN replacement has been performedand the DNN replacement is to be performed with recognition of the UE100, the AMF 120 may include only the selected DNN in the PDU sessionestablishment accept message without the requested DNN, or may includeboth the requested DNN and the selected DNN. If only the selected DNN isincluded in the PDU session establishment accept message, the UE 100 mayidentify that the requested DNN transmitted by the UE 100 in operation403 is different from the selected DNN received in operation 448, andmay determine that the selected DNN is used for the PDU session due tothe occurrence of DNN replacement. Alternatively, in the case where therequested DNN and the selected DNN are included in the PDU sessionestablishment accept message, the UE 100 may determine that the UE 100has requested for the requested DNN, but the selected DNN is used forthe PDU session. The UE 100, which has completed the PDU sessionestablishment, may store PDU session related information (e.g., the PDUsession ID, the requested DNN and/or selected DNN used for the PDUsession, the requested S-NSSAI and/or selected S-NSSAI used for the PDUsession, and the like).

In operation 454, the UE 100 having received the PDU sessionestablishment accept message in operation 448 may start uplink datatransmission.

In operation 457, the AMF 120 may transmit anNsmf_PDUSession_UpdateSMContext Request message to the SMF 135.

In operation 460, the SMF 135 may transmit an N4 session modificationrequest message to the UPF 130. In operation 463, the UPF 130 maytransmit an N4 session modification response message to the SMF 135.

In operation 466, the SMF 135 may perform a registration procedure withthe UDM 145.

In operation 469, the UPF 130 may start downlink data transmission tothe UE 100.

In operation 472, the SMF 135 may transmit anNsmf_PDUSession_UpdateSMContext Response message to the AMF 120.

In operation 475, the SMF 135 may perform an unsubscribe procedure withthe UDM 145.

FIG. 5 illustrates a procedure of updating UE configuration informationaccording to an embodiment of the disclosure.

Referring to FIG. 5, in operation 503, the AMF 120 may transmit a policyinformation update request message to the PCF 140. The message inoperation 503 may be the message in operation 230 a of FIG. 3, themessage in operation 236 ba, and the message in operation 404 of FIG. 4.

In operation 506, the PCF 140 may determine to update UE policyinformation. For example, if there are many requests for DNN replacementor S-NSSAI replacement for the same DNN or the same S-NSSAI, the PCF 140may determine to update the UE policy information.

In operation 509, the PCF 140 may transmit aNamf_Communication_N1N2MessageTransfer message to the AMF 120. Thepolicy container included in the Namf_Communication_N1N2MessageTransfermessage may include at least one of DNN information associated with anapplication (for example, identified by a combination of OSId andOSAppId), a DNN priority, equivalent DNN information that can be used inthe same manner as the DNN, and the identifier of the UE 100 (e.g.,SUPI, 5G-GUTI, and the like).

If the UE 100 is in an idle mode, in operation 512, the AMF 120 mayperform a network triggered Service Request.

In operation 515, the AMF 120 may transmit a policy container receivedfrom the PCF 140 to the UE 100. The UE 100 may store and use information(e.g., UE route selection policy (URSP), and the like) included in thereceived policy container. According to an embodiment of the disclosure,the information of the policy container received by the UE 100 mayinclude one or more DNNs. Alternatively, according to an embodiment ofthe disclosure, the information of the policy container received by theUE 100 may include one or more DNNs and a priority for each DNN.Alternatively, according to an embodiment of the disclosure, theinformation of the policy container received by the UE 100 may includeone or more DNNs and a DNN (hereinafter, referred to as equivalent DNN)that can be used in the same manner as the DNNs.

The UE 100 according to an embodiment may establish a PDU sessionthrough the procedure shown in FIG. 4, and store PDU session relatedinformation (e.g., a PDU session ID, a requested DNN and/or the selectedDNN used for a PDU session, and a requested S-NSSAI and/or a selectedS-NSSAI used for the PDU session). In operation 515, the UE 100 havingreceived the policy container may compare the PDU session-relatedinformation stored in the UE 100 and the information included in thereceived policy container, and various methods are possible as follows.

For example, in the case where one or more DNNs are included in theinformation of the policy container received by the UE 100, that is, theequivalent DNN is not included therein, and in the case where the PDUsession related information, stored by the UE 100, includes one DNN (forexample, the requested DNN or the selected DNN), the UE 100 may identifywhether the DNN for the PDU session is included in the received policycontainer information, and if the DNN for the PDU session is notincluded in the information of the received policy container, the UE 100may release the corresponding PDU session.

According to another example, in the case where one or more DNNs areincluded in the information of the policy container received by the UE100, that is, the equivalent DNN is not included therein, and in thecase where the PDU session related information, stored by the UE 100,includes two DNNs (for example, the requested DNN and the selected DNN),the UE 100 may identify whether the selected DNN for the PDU session isincluded in the received policy container information, and if the DNNfor the PDU session is not included in the information of the receivedpolicy container, the UE 100 may release the corresponding PDU session.

According to still another example, in the case where one or more DNNsand equivalent DNNs that can be used in the same manner as the DNNs areincluded in the information of the policy container received by the UE100, and one DNN (e.g., the requested DNN or selected DNN) is stored inthe PDU session related information stored by the UE 100, the UE 100identifies whether the DNN for the PDU session is included, as a DNN orequivalent DNN, in the received policy container information, and if theDNN for the PDU session is not included in the policy containerinformation, the UE 100 may release the corresponding PDU session.

According to further another example, in the case where one or more DNNsand equivalent DNNs that can be used in the same manner as the DNNs areincluded in the information of the policy container received by the UE100, and two DNNs (e.g., the requested DNN and the selected DNN) arestored in the PDU session related information stored by the UE 100, theUE 100 identifies whether the selected DNN for the PDU session isincluded, as a DNN or equivalent DNN, in the received policy containerinformation, and if the selected DNN for the PDU session is not includedin the policy container information, the UE 100 may release thecorresponding PDU session.

According to still further another example, in the case where one ormore DNNs and a priority for each DNN are included in the information ofthe policy container received by the UE 100, the UE 100 may identifywhether the DNN for the PDU session is included, as a DNN, in thereceived policy container information. If the DNN for the PDU session isincluded in the policy container information, the UE 100 may maintainthe PDU session. For example, the information of the policy containermay include DNN #1, DNN #2, and DNN #3 as DNNs for the application, DNN#1 may be priority 1, DNN #2 may be priority 2, and DNN #3 may bepriority 3. The PDU session for the application may be established withDNN #2. The UE may identify that DNN #2 for the PDU session is includedas DNN #2 included in the policy container information, and may maintainthe PDU session. Thereafter, in the case where a PDU session is requiredfor an application using DNN #1, the UE 100 may reuse the PDU sessionalready established with DNN #2 and transmit data traffic, instead ofgenerating a new PDU session with DNN #1. Thereafter, the PDU sessionestablished with DNN #2 by the UE 100 may be released. If the PDUsession is required for an application using DNN #1 after the PDUsession established with DNN #2 is released, the UE may requestgeneration of a new PDU session with DNN #1.

In operation 518, the UE 100 may transmit, to the AMF 120, aconfirmation message indicating that the policy container informationhas been successfully received in operation 515. The UE 100 may use thelatest policy information received in a subsequent PDU sessionestablishment procedure.

In operation 521, the AMF 120 may transmit a Namf_N1MessageNotifymessage to the PCF 140.

Embodiment 3

Embodiment 3 describes a method for managing information of parameterstransmitted by a UE and replaced parameters, by the UE and a network.

The UE 100 according to an embodiment may perform registration in the 5Gsystem through the procedure illustrated in FIG. 2. In operation 203,the UE 100 may include network slice information (hereinafter, referredto as Requested NSSAI) to be used by the UE after registering thenetwork slice information in the 5G system. The AMF 120, which hasreceived the registration request message, may determine a registrationarea (RA) and allowed network slice information (hereinafter, AllowedNSSAI) that can be used by the UE after registering the same in the 5Gsystem based on the received Requested NSSAI information, localconfiguration of the AMF, the UE subscription information, andinformation, such as the current network situation, after operation 203.In operation 236 a, the AMF 120 may transmit the registration acceptmessage including the Allowed NSSAI and the RA to the UE 100. The UE 100may store the received Allowed NS SAI and RA, and then use the storedAllowed NS SAI and RA in the subsequent procedure.

The UE 100 according to an embodiment may establish a PDU sessionthrough the procedure illustrated in FIG. 4 after completing theregistration in the 5G system. Prior to performing operation 403, the UE100 may select an S-NSSAI associated with an application to be used bythe UE 100, based on local configuration information stored in the UE100. In addition, the UE may determine whether the selected S-NSSAI isincluded in the Allowed NSSAI, which is received in operation 236 a andstored by the UE 100. If the selected S-NSSAI is included in the AllowedNSSAI, in operation 403, the UE 100 may include, in the PDU sessionestablishment request transmitted to the AMF 120, the selected S-NSSAI(hereinafter, referred to as requested S-NSSAI) and the PDU session IDassigned by the UE itself.

Upon receiving the PDU session establishment request, the AMF 120 maydetermine to perform S-NSSAI replacement. In operation 404, the AMF 120may determine the selected S-NSSAI to replace the requested S-NSSAI,requested by the UE through operation 406. The AMF 120 may store the PDUsession ID, the requested S-NSSAI, and the selected S-NSSAI as the UEcontext of the UE 100.

In operations 445 and 448, the AMF 120 may transmit a PDU sessionestablishment accept message to the UE 100 through the base station 110.The PDU session establishment accept may include at least one of the PDUsession ID, the requested S-NSSAI, and the selected S-NSSAI. Forexample, if S-NSSAI replacement is not performed, the AMF 120 mayinclude only the requested S-NSSAI in the PDU session establishmentaccept message. Alternatively, if S-NSSAI replacement has been performedand the S-NSSAI replacement is to be performed without recognition ofthe UE 100, the AMF 120 may include only the requested S-NSSAI in thePDU session establishment accept message without the selected S-NSSAI.Alternatively, if the S-NSSAI replacement has been performed and theS-NSSAI replacement is to be performed with recognition of the UE 100,the AMF 120 may include only the selected S-NSSAI in the PDU sessionestablishment accept message without the requested S-NSSAI, or mayinclude both the requested S-NSSAI and the selected S-NSSAI. If only theselected S-NSSAI is included in the PDU session establishment acceptmessage, the UE 100 may identify that the requested S-NSSAI transmittedby the UE 100 in operation 403 is different from the selected S-NSSAIreceived in operation 448, and may determine that the selected S-NSSAIis used for the PDU session due to the occurrence of S-NSSAIreplacement. Alternatively, in the case where the requested S-NSSAI andthe selected S-NSSAI are included in the PDU session establishmentaccept message, the UE 100 may request the requested S-NSSAI, but maydetermine that the selected S-NSSAI is used for the PDU session. The UE100, which has completed the PDU session establishment, may store PDUsession related information (e.g., the PDU session ID, the requestedS-NSSAI and/or the selected S-NSSAI used for the PDU session, and thelike).

The UE 100 according to an embodiment may support the mobility, uses aPDU session after establishing a PDU session, and leave the RA areareceived by the UE 100 from the AMF 200. The UE having left the RA areamay perform mobility registration in the 5G system through the procedureillustrated in FIG. 2. In operation 203, the UE 100 may transmit aregistration request message for mobility registration to the AMF 120.The registration request message may include the network sliceinformation (hereinafter, referred to as Requested NSSAI) to be used bythe UE 100 after registering mobility in the 5G system and/or PDUsession information (e.g., the PDU session ID) to be continuouslyexecuted by the UE 100. At this time, the UE 100 may include, in theRequested NSSAI, an S-NSSAI (e.g., the requested S-NSSAI and/or theselected S-NSSAI) related to the PDU session being used by the UE 100.

In operation 209, the AMF 120 may discover an AMF previously serving theUE 100, that is, the old AMF 200, based on the received identifier ofthe UE 100 (e.g., SUPI or 5G-GUTI). In operation 212, the AMF 120 maytransmit a Namf_Communication_UEContextTransfer message requesting theUE context to the old AMF 200. The Namf_Communication_UEContextTransfermessage may include the identifier of the UE 100 (e.g., SUPI or5G-GUTI). The old AMF 200 identifies whether the UE context of thecorresponding UE 100 is stored, and if the UE context exists, the oldAMF 200 may include the UE context of the UE 100 in theNamf_Communication_UEContextTransfer response message transmitted inoperation 215. The UE context may include at least one of a PDU sessionID being used by the UE 100, and a requested DNN, a selected DNN, arequested S-NSSAI, and a selected S-NSSAI, which are associated with thePDU session ID. The AMF 120 having received theNamf_Communication_UEContextTransfer response message may store thereceived UE context information.

Alternatively, in operation 224 d, the AMF 120 may acquire, from the UDM145, the UE 100 related information (e.g., access and mobilitysubscription data, SMF selection subscription data, UE context,subscribed DNNs, subscribed S-NSSAIs, and the like). The UE 100 relatedinformation may include PDU session information of the UE 100. Forexample, the PDU session information may include at least one of a PDUsession ID being used by the UE 100, and a requested DNN, a selectedDNN, a requested S-NSSAI, and a selected S-NSSAI, which are associatedwith the PDU session ID. The AMF 120 may store the UE 100 relatedinformation received from the UDM 145.

Alternatively, in operation 230, the AMF 120 may acquire, from the PCF140, the UE 100 related information (e.g., access and mobilitysubscription data, SMF selection subscription data, UE context,subscribed DNNs, subscribed S-NSSAIs, and the like). The UE 100 relatedinformation may include PDU session information of the UE 100. Forexample, the PDU session information may include at least one of a PDUsession ID being used by the UE 100, and a requested DNN, a selectedDNN, a requested S-NSSAI, and a selected S-NSSAI, which are associatedwith the PDU session ID. The AMF 120 may store the UE 100 relatedinformation received from the PCF 140.

The AMF 120, which has received the registration request message, maydetermine a registration area (RA) and allowed network slice information(hereinafter, Allowed NS SAI) that can be used by the UE afterregistering the same in the 5G system based on the received RequestedNSSAI information, the AMF local configuration, the UE subscriptioninformation, and information, such as the current network situation,after operation 203. Further, in determining the Allowed NSSAI, the AMF120 may consider UE context information received from the old AMF 200 inoperation 215, UE information received from the UDM 145 in operation 225d, and UE information received from the PCF 140 in operation 230. Forexample, the AMF 120 may include, in the Allowed NSSAI, the selectedS-NSSAI included in the UE context or UE information.

In operation 233, the AMF 120 may manage a PDU session to becontinuously executed by the UE 100. The AMF 120 may acquire the S-NSSAI(e.g., the requested S-NSSAI and/or the selected S-NSSAI) informationassociated with the PDU session being used by the UE 100, from UEcontext information received from the old AMF 200 in operation 215, UEinformation received from the UDM 145 in operation 225 d, or UEinformation received from PCF 140 in operation 230, and may manage thePDU session based on S-NSSAI information associated with the PDUsession. Further, the AMF 120 may use Allowed NS SAI informationdetermined by the AMF 120 at the time of managing the PDU session.

For example, AMF 120 may identify whether the selected S-NSSAI of thePDU session is included in the Allowed NSSAI. If the selected S-NSSAI isnot included in the Allowed NSSAI, the AMF 120 may release thecorresponding PDU session. Alternatively, even if the selected S-NSSAIis not included in the Allowed NSSAI, if the requested S-NSSAI isincluded in the Allowed NSSAI, the AMF 120 may continue to maintain thecorresponding PDU session without releasing the same.

According to another example, the AMF 120 may identify whether therequested S-NSSAI of the PDU session is included in the Allowed NSSAI.If the requested S-NSSAI is not included in the Allowed NSSAI, the AMF120 may release the corresponding PDU session.

In operation 236 a, the AMF may transmit the registration accept messageincluding the Allowed NSSAI and RA to the UE 100. The UE 100 may storethe received Allowed NSSAI and RA and use the stored Allowed NSSAI andRA in the subsequent procedure.

If S-NSSAI replacement occurs, the AMF 120 according to an embodimentmay store, as the UE context, S-NSSAI (requested S-NSSAI) requested bythe UE as well as S-NSSAI (selected S-NSSAI) associated with a PDUsession, and thus may maintain the session of the UE in the case wherethe UE mobility registration occurs.

FIG. 6 illustrates a structure of a UE according to an embodiment of thedisclosure.

Referring to FIG. 6, the UE may include a transceiver 610, a controller620, and a storage 630. In the disclosure, the controller may be definedas a circuit, an application-specific integrated circuit, or at leastone processor.

The transceiver 610 may transmit or receive signals to or from anothernetwork entity. The transceiver 610 may receive system information froma base station, for example, and may receive a synchronization signal ora reference signal.

The controller 620 may control the overall operations of the UEaccording to an embodiment proposed in the disclosure. For example, thecontroller 620 may control a signal flow between blocks so as to performoperations according to the procedures described above with reference toFIGS. 1A to 5. For example, the controller 620 may control operationsproposed by the disclosure in order to replace DNN and/or S-NS SAI in awireless communication system according to an embodiment.

The storage 630 may store at least one of information transmitted orreceived through the transceiver 610 and information generated throughthe controller 620. For example, the storage 630 may store information(e.g., DNN-related information, S-NSSAI-related information, UEconfiguration information, and the like) used in the procedures relatedto DNN and/or S-NSSAI replacement according to the embodiment describedabove.

FIG. 7 illustrates a structure of a base station according to anembodiment of the disclosure.

Referring to FIG. 7, the base station may include a transceiver 710, acontroller 720, and a storage 730. In the disclosure, the controller maybe defined as a circuit, an application-specific integrated circuit, orat least one processor.

The transceiver 710 may transmit or receive signals to or from anothernetwork entity. The transceiver 710 may transmit system information tothe UE, for example, and may transmit a synchronization signal or areference signal.

The controller 720 may control the overall operations of the basestation according to the embodiment proposed in the disclosure. Forexample, the controller 720 may control a signal flow between blocks inorder to perform operations according to the procedures described abovewith reference to FIGS. 1A to 5. Specifically, the controller 720 maycontrol the operation proposed by the disclosure in order to replace DNNand/or S-NSSAI in a wireless communication system according to theembodiment.

The storage 730 may store at least one of information transmitted orreceived through the transceiver 710 and information generated throughthe controller 720. For example, the storage 730 may store information(e.g., DNN-related information, S-NSSAI-related information, and thelike) used in procedures related to DNN and/or S-NSSAI replacementaccording to the embodiment described above.

FIG. 8 illustrates a structure of an AMF according to an embodiment ofthe disclosure.

Referring to FIG. 8, the AMF may include a transceiver 810, a controller820, and a storage 830. In the disclosure, the controller may be definedas a circuit, an application-specific integrated circuit, or at leastone processor.

The transceiver 810 may transmit or receive signals to or from anothernetwork entity. The transceiver 810 may receive, for example, systeminformation from a base station, and may receive a synchronizationsignal or a reference signal.

The controller 820 may control the overall operations of the AMFaccording to the embodiment proposed in the disclosure. For example, thecontroller 820 may control a signal flow between blocks so as to performoperations according to the procedures described above with reference toFIGS. 1A to 5. For example, the controller 820 may control an operationproposed by the disclosure in order to replace DNN and/or S-NS SAI in awireless communication system according to an embodiment.

The storage 830 may store at least one of information transmitted orreceived through the transceiver 810 and information generated throughthe controller 820. For example, the storage 630 may store information(e.g., DNN-related information, S-NSSAI-related information, and thelike) used in procedures related to DNN and/or S-NSSAI replacementaccording to the above-described embodiment.

FIG. 9 illustrates a structure of a PCF according to an embodiment ofthe disclosure.

Referring to FIG. 9, the PCF may include a transceiver 910, a controller920, and a storage 930. In the disclosure, the controller may be definedas a circuit, an application-specific integrated circuit, or at leastone processor.

The transceiver 910 may transmit or receive signals to or from anothernetwork entity. The transceiver 910 may transmit system information tothe base station, for example, and may transmit a synchronization signalor a reference signal.

The controller 920 may control the overall operations of the PCFaccording to the embodiment proposed in the disclosure. For example, thecontroller 920 may control a signal flow between blocks so as to performoperations according to the procedures described above with reference toFIGS. 1A to 5. Specifically, the controller 920 may control theoperation proposed by the disclosure in order to replace DNN and/or S-NSSAI in a wireless communication system according to an embodiment.

The storage 930 may store at least one of information transmitted orreceived through the transceiver 910 and information generated throughthe controller 920. For example, the storage 930 may store information(e.g., DNN-related information, S-NSSAI-related information, and thelike) used in procedures related to DNN and/or S-NSSAI replacementaccording to the embodiment described above.

FIG. 10 illustrates a structure of an NRF or SCP according to anembodiment of the disclosure.

Referring to FIG. 10, the NRF or SCP may include a transceiver 1010, acontroller 1020, and a storage 1030. In the disclosure, the controllermay be defined as a circuit, an application-specific integrated circuit,or at least one processor.

The transceiver 1010 may transmit or receive signals to or from anothernetwork entity. The transceiver 1010 may transmit system information tothe base station, for example, and may transmit a synchronization signalor a reference signal.

The controller 1020 may control the overall operations of the NRF or SCPaccording to the embodiment proposed in the disclosure. For example, thecontroller 1020 may control a signal flow between each block so as toperform operations according to the procedures described above withreference to FIGS. 1A to 5. Specifically, the controller 1020 maycontrol the operation proposed by the disclosure in order to replace DNNand/or S-NSSAI in a wireless communication system according to anembodiment.

The storage 1030 may store at least one of information transmitted orreceived through the transceiver 1010 and information generated throughthe controller 1020. For example, the storage 1030 may store information(e.g., DNN-related information, S-NSSAI-related information, and thelike) used in procedures related to DNN and/or S-NSSAI replacementaccording to the embodiment described above.

Although not explicitly shown in the disclosure, the network entitiesshown in FIGS. 1A to 5 (e.g., SMF, UDM, UPF, data network (DN), and thelike) may have the same or similar structures to those shown in FIGS. 6to 10. For example, SMF, UDM, UPF, DN, and the like, may include atransceiver, a controller, and/or a storage.

In this case, the transceiver may transmit or receive signals to or fromanother network entity. The transceiver may transmit system informationto the base station, for example, and may transmit a synchronizationsignal or a reference signal.

The controller may control the overall operations of the correspondingnetwork entity according to the embodiment proposed in the disclosure.For example, the controller may control a signal flow between each blockso as to perform an operation according to the procedures describedabove with reference to FIGS. 1A to 5. Specifically, the controller maycontrol the operation proposed in the disclosure in order to replace DNNand/or S-NSSAI in a wireless communication system according to theembodiment.

The storage may store at least one of information transmitted orreceived through the transceiver and information generated through thecontroller. For example, the storage may store information (e.g.,DNN-related information, S-NSSAI-related information, and the like) usedin procedures related to DNN and/or S-NSSAI replacement according to theembodiment described above.

While the disclosure has been shown and described with reference tovarious embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the disclosure as definedby the appended claims and their equivalents.

What is claimed is:
 1. A method performed by an access and mobilitymanagement function (AMF) in a mobile communication system, the methodcomprising: selecting a policy control function (PCF) for a replacementof data network name (DNN), based on a received registration requestmessage from a user equipment (UE); transmitting, to the PCF, allowednetwork slice selection assistance information (NSSAI) for the UE;receiving, from the PCF, first list information on the replacement ofDNN, based on the allowed NSSAI; receiving, from the UE, a protocol dataunit (PDU) session establishment request message including single NSSAI(S-NSSAI) for a PDU session and a UE requested DNN; and determining toperform a replacement of the UE requested DNN, based on the first listinformation.
 2. The method of claim 1, wherein the first listinformation includes at least one of S-NSSAI, and wherein each of the atleast one of S-NSSAI corresponds to second list information including atleast one of DNN.
 3. The method of claim 2, wherein, in case that theS-NSSAI for the PDU session corresponds to the at least one of S-NSSAIincluded in the first list information and the UE requested DNNcorresponds to the at least one of DNN included in the second listinformation, the replacement of the UE requested DNN is performed, andwherein, in case that the UE requested DNN is not supported by a networkand the UE requested DNN is not indicated for replacement in the secondlist information, a registration request of the UE is rejected with acause value.
 4. The method of claim 1, wherein the selecting the PCF forthe replacement of DNN further comprises: transmitting, to a networkrepository function (NRF), a network function (NF) discovery requestmessage including capability information to indicate that the PCFsupporting a capability for the replacement of DNN is preferred; andreceiving, from the NRF, an NF discovery response message includingcapability information to indicate whether or not the PCF supports thereplacement of DNN.
 5. The method of claim 1, further comprising:transmitting, to the PCF, a message to request for the replacement ofthe UE requested DNN including information on the S-NSSAI for the PDUsession and the UE requested DNN; and receiving, from the PCF, aselected DNN by the PCF, wherein the UE requested DNN is replaced by theselected DNN.
 6. A method performed by a policy control function (PCF)in mobile a communication system, the method comprising: transmitting,to a network repository function (NRF), a network function (NF) registerrequest message including capability information of the PCF to indicatewhether or not the PCF supports a replacement of data network name(DNN); receiving, from the NRF, an NF register request response messagefor an acknowledgement that an NF register request is accepted;receiving, from an access and mobility management function (AMF),allowed network slice selection assistance information (NSSAI) for auser equipment (UE); and transmitting, to the AMF, first listinformation on the replacement of DNN, based on the allowed NSSAI,wherein a protocol data unit (PDU) session establishment request messageincluding single NSSAI (S-NSSAI) for the PDU session and a UE requestedDNN is transmitted to the AMF from the UE and a replacement of the UErequested DNN is performed based on the first list information.
 7. Themethod of claim 6, wherein the first list information includes at leastone of S-NSSAI, and wherein each of the at least one of S-NSSAIcorresponds to second list information including at least one of DNN. 8.The method of claim 7, wherein, in case that the S-NSSAI for the PDUsession corresponds to the at least one of S-NSSAI included in the firstlist information and the UE requested DNN corresponds to the at leastone of DNN included in the second list information, the replacement ofthe UE requested DNN is performed, and wherein, in case that the UErequested DNN is not supported by a network and the UE requested DNN isnot indicated for replacement in the second list information, aregistration request of the UE is rejected with a cause value.
 9. Themethod of claim 6, further comprising: receiving, from the AMF, amessage to request for the replacement of the UE requested DNN includinginformation on the S-NSSAI for the PDU session and the UE requested DNN;and transmitting, to the AMF, a selected DNN by the PCF, wherein the UErequested DNN is replaced by the selected DNN.
 10. A method performed bya network repository function (NRF) in a mobile communication system,the method comprising: receiving, from a policy control function (PCF),a network function (NF) register request message including capabilityinformation of the PCF to indicate whether or not the PCF supports areplacement of data network name (DNN); transmitting, to the PCF, an NFregister request response message for an acknowledgement that an NFregister request is accepted; receiving, from an access and mobilitymanagement function (AMF), an NF discovery request message includingcapability information to indicate that the PCF supporting a capabilityfor the replacement of DNN is preferred; and transmitting, to the AMF,an NF discovery response message including capability information toindicate whether or not the PCF supports the replacement of DNN.
 11. Anaccess and mobility management function (AMF) in a mobile communicationsystem, the AMF comprising: a transceiver; and at least one processorconfigured to: select a policy control function (PCF) for a replacementof data network name (DNN), based on a received registration requestmessage from a user equipment (UE), control the transceiver to transmit,to the PCF, allowed network slice selection assistance information(NSSAI) for the UE, control the transceiver to receive, from the PCF,first list information on the replacement of DNN, based on the allowedNSSAI, control the transceiver to receive, from the UE, a protocol dataunit (PDU) session establishment request message including single NSSAI(S-NSSAI) for a PDU session and a UE requested DNN, and determine toperform a replacement of the UE requested DNN, based on the first listinformation.
 12. The AMF of claim 11, wherein the first list informationincludes at least one of S-NSSAI, and wherein each of the at least oneof S-NSSAI corresponds to second list information including at least oneof DNN.
 13. The AMF of claim 12, wherein, in case that the S-NSSAI forthe PDU session corresponds to the at least one of S-NSSAI included inthe first list information and the UE requested DNN corresponds to theat least one of DNN included in the second list information, thereplacement of the UE requested DNN is performed, and wherein, in casethat the UE requested DNN is not supported by a network and the UErequested DNN is not indicated for replacement in the second listinformation, a registration request of the UE is rejected with a causevalue.
 14. The AMF of claim 11, wherein the at least one processor isfurther configured to: control the transceiver to transmit, to a networkrepository function (NRF), a network function (NF) discovery requestmessage including capability information to indicate that the PCFsupporting a capability for the replacement of DNN is preferred, andcontrol the transceiver to receive, from the NRF, an NF discoveryresponse message including capability information to indicate whether ornot the PCF supports the replacement of DNN.
 15. The AMF of claim 11,wherein the at least one processor is further configured to: control thetransceiver to transmit, to the PCF, a message to request for thereplacement of the UE requested DNN including information on the S-NSSAIfor the PDU session and the UE requested DNN, and control thetransceiver to receive, from the PCF, a selected DNN by the PCF, whereinthe UE requested DNN is replaced by the selected DNN.
 16. A policycontrol function (PCF) in mobile a communication system, the PCFcomprising: a transceiver; and at least one processor configured to:control the transceiver to transmit, to a network repository function(NRF), a network function (NF) register request message includingcapability information of the PCF to indicate whether or not the PCFsupports a replacement of data network name (DNN), control thetransceiver to receive, from the NRF, an NF register request responsemessage for an acknowledgement that an NF register request is accepted,control the transceiver to receive, from an access and mobilitymanagement function (AMF), allowed network slice selection assistanceInformation (NSSAI) for a user equipment (UE), and control thetransceiver to transmit, to the AMF, first list information on thereplacement of DNN, based on the allowed NSSAI, wherein a protocol dataunit (PDU) session establishment request message including single NSSAI(S-NSSAI) for the PDU session and a UE requested DNN is transmitted tothe AMF from the UE and a replacement of the UE requested DNN isperformed based on the first list information.
 17. The PCF of claim 16,wherein the first list information includes at least one of S-NSSAI, andwherein each of the at least one of S-NSSAI corresponds second listinformation including to at least one of DNN.
 18. The PCF of claim 17,wherein, in case that the S-NSSAI for the PDU session corresponds to theat least one of S-NSSAI included in the first list information and theUE requested DNN corresponds to the at least one of DNN included in thesecond list information, the replacement of the UE requested DNN isperformed, and wherein, in case that the UE requested DNN is notsupported by a network and the UE requested DNN is not indicated forreplacement in the second list information, a registration request ofthe UE is rejected with a cause value.
 19. The PCF of claim 16, whereinthe at least one processor is further configured to: control thetransceiver to receive, from the AMF, a message to request for thereplacement of the UE requested DNN including information on the S-NSSAIfor the PDU session and the UE requested DNN, and control thetransceiver to transmit, to the AMF, a selected DNN by the PCF, whereinthe UE requested DNN is replaced by the selected DNN.
 20. A networkrepository function (NRF) in a mobile communication system, the NRFcomprising: a transceiver; and at least one processor configured to:control the transceiver to receive, from a policy control function(PCF), a network function (NF) register request message includingcapability information of the PCF to indicate whether or not the PCFsupports a replacement of data network name (DNN), control thetransceiver to transmit, to the PCF, an NF register request responsemessage for an acknowledgement that an NF register request is accepted,control the transceiver to receive, from an access and mobilitymanagement function (AMF), an NF discovery request message includingcapability information to indicate that the PCF supporting a capabilityfor the replacement of DNN is preferred, and control the transceiver totransmit, to the AMF, an NF discovery response message includingcapability information to indicate whether or not the PCF supports thereplacement of DNN.